1. Field of the Invention
This invention pertains to tensioning devices, and more particularly to apparatus for adjusting the tension of drive belts.
2. Description of the Prior Art
Various equipment has been developed to adjust the tension of flexible drive belts. Such equipment includes movable idler pulleys or rollers that press transversely against a belt to take up slack.
Tensioning heavy conveyor belts poses particularly difficult problems, because such belts are usually very long and stiff in the longitudinal direction. Prior conveyor belt tensioning devices include four-sided frames fastened to both sides of the conveyor bed. A pair of special pillow blocks support the conveyor end roller. The pillow blocks are adjusted longitudinally with respect to the conveyor bed by means of threaded studs that engage the tensioner frames. Such apparatus possesses the important disadvantage of exposing the adjusting components to the elements and accidental damage. In addition, the tensioner frames protrude beyond the conveyor end roller, thereby increasing overall conveyor length, and the special pillow blocks required add undesirable expense.
An exemplary conveyor belt tensioner is described in U.S. Pat. No. 3,832,910, the disclosure of which is incorporated by reference herein. In the tightener of the 3,832,910 patent, telescoping tubes lie along each side of the conveyor bed. Conventional roller supporting pillow blocks are mounted at one end of the inner tubes, which are supported by and reciprocate within associated outer tubes. The inner tubes are relatively reciprocable for belt tension adjustment by appropriately designed and protected threaded rods and nuts. The telescoping design eliminates the need for any tensioner parts to extend beyond the end roller. Consequently, tensioner space and expense are reduced.
Although the belt tensioner of the 3,832,910 patent has proven very successful, it nevertheless is subject to improvement. A particularly desirable improvement is a device that more quickly adjusts the belt tension for conveyor servicing than is achieved through the threaded adjustment rods.